The present invention relates to refrigerators, and in particular, to refrigerators which defrost after a forced pre-cooling.
Construction of a well known prior art refrigerator is shown in FIG. 1. Such refrigerator is formed with an outer cabinet 3 and inner cabinet 5. Outer cabinet 3 and inner cabinet 5 establish a heat insulation chamber 7 which is filled with a heat insulation material. The inside of inner cabinet 5 is divided into two chambers. One is a freezing chamber 9 and the other is a refrigerating chamber 11 with a partition wall 13 therebetween. An evaporator 10 and a fan-motor 12 are provided within a cooling chamber 15, which is located between partition wall 13 and the bottom surface 17 of freezing chamber 9. A shelf 19 is supported at the upper part of freezing chamber 9.
One end 23a of a first cooling path 23 opens into freezing chamber 9 while the other end 23b thereof opens into cooling chamber 15. Second cooling path 25 is formed at the back of refrigerating chamber 11 such that one end 25a thereof opens into cooling chamber 15 while the other end 25b thereof communicates with refrigerating chamber 11 through a damper 27. Damper 27 is a conventional temperature controller which regulates the temperature of refrigerating chamber 11. A third cooling path 29 is provided at the front of cooling chamber 15 to communicate cooling chamber 15 with freezing chamber 9. Thus, a first air circulation path is established so that cooled air flows from cooling chamber 15 through first cooling path 23 to freezing chamber 9 and then returns to cooling chamber 15 via third cooling path 29.
Cooling path 31 is also provided at the front of cooling chamber 15 to communicate cooling chamber 15 with refrigerating chamber 11. Thus, a second air circulation path is also established so that cooled air flows from cooling chamber 15 to refrigerating chamber 11 through second cooling path 25 and damper 27 and then returns to cooling chamber 15 via fourth cooling path 31.
Several shelves 33 are provided in parallel with each other within refrigerating chamber 11, and a vegetable case 35 is slidably provided on the bottom part of refrigerating chamber 11. A compressor unit 37 is provided on the bottom rear portion below refrigerating chamber 11 to supply coolant to the evaporator 10 via suitable conduits (not shown). Freezing chamber 9 and refrigerating chamber 11 are opened and closed by individual doors 39 and 40 provided in front thereof. Each door 39 and 40 is provided with individual handles 39a and 40a on the front surfaces thereof.
The above-described refrigerator has two cooling functions, that is, a regular cooling function and a rapid cooling function.
In the regular cooling operation, refrigerating chamber 11 and freezing chamber 9 are each automatically controlled to its individual predetermined temperature.
In the rapid cooling operation, cooled air is provided only to freezing chamber 9 when a user manually commands this function. The temperature of freezing chamber 9 therefore goes down quickly under -40.degree. C. within prescribed minutes to freeze food rapidly.
After a certain period of usage, frost may accumulate on evaporator 10 and defrosting is carried out automatically. Conventional defrosting will be described as follows.
As can be seen in line A of FIG. 2, before the defrost operation begins, a pre-cooling operation is carried out to cool refrigerating chamber 9 to a prescribed temperature, compensating for the temperature which will rise while defrosting is carried out. This is accomplished by driving the compressor 37 forcibly for a prescribed period of time. In this case, if a user commands the rapid cooling operation when the pre-cooling operation is being carried out, the rapid cooling operation is carried out in preference to the pre-cooling operation. After the completion of the rapid cooling operation, the pre-cooling operation is re-executed for only the remaining period of time as is shown in line B of FIG. 2. If the precooling operation is intended to begin when the rapid cooling operation is being carried out, the rapid cooling operation is carried out in preference to the pre-cooling operation, and then the pre-cooling operation is executed later. After the pre-cooling operation is completed, defrosting is carried out until the temperature of the evaporator reaches a prescribed temperature as is shown in line C of FIG. 2.
The above-described operation has drawbacks, that is, the rapid cooling operation is carried out in spite of the pre-cooling operation when the rapid cooling operation is ordered while the pre-cooling operation is being carried out. Consequently, power consumption of the compressor is increased because of its excessive use and the freezing chamber is cooled excessively due to the continuous execution of the rapid cooling and pre-cooling operations.